Histological and histochemical studies of digestive system in the megrim, Lepidorhombus whiffiagonis (Teleostei: Scophthalmidae)

The digestive system of Lepidorhombus whiffiagonis was studied using histological and histochemical techniques. The wall of oesophagus and stomach fundus consisted of four histological layers: mucosa, submucosa, muscularis and the outer layer. Mucosa, the innermost layer, usually consisted of three different layers, including epithelium, lamina propria and lamina muscularis mucosae. Submucosa of connective tissue with blood vessels and nerve fibres underlined the mucosa and usually protrudes into the mucosal folds except in the gallbladder where it is completely absent. The muscular layer of the digestive system consisted of smooth muscles arranged in longitudinal, circular or oblique layers. Striated fibres were found in the oesophageal wall. The outermost layer comes as tunica adventitia in upper parts and tunica serosa in lower parts of the digestive system. Hepatocytes were surrounded by a mass of fat-storing cells. Serous acini of pancreas were scattered down the length of the stomach. Alcian blue/PAS technique revealed that alkaline and neutral mucopolysaccharides were present in oesophagus while acidic mucopoly-saccharides was found in the stomach and intestines.